Commercial lawn care companies usually distribute lawn care and agricultural chemicals when the sun is shining and do not generally concern themselves if a rain storm occurs too soon after the chemicals have been applied to allow the chemicals to be absorbed by the soil. In addition, since the chemicals supplied by commercial distributors must last a considerable period of time until the next visit, very concentrated dosages of chemicals are used. This may be unhealthy for lawns, not to mentions humans and pets.
Spreading too much fertilizer or pesticide onto lawns and crops may also result in run-off into ponds, rivers and oceans. Marine biologists have suggested a possible link between decreasing crab and oyster harvests from the Chesapeake Bay and fertilizer run-off from farms. If farmers could control the timing, as well as the amount, of fertilizer they spread on their crops, less run-off may result.
Common methods of applying pesticides and fertilizers include the use of push-type granular spreaders or the spreading of dry chemicals by hand. Hand-held sprayers which attach to garden hoses are also commonly used to spread chemicals; one such sprayer is described in U.S. Pat. No. 2,724,583 (Targosh et al) which uses a venturi near the nozzle of a hose to create a suction to draw chemicals from an attached container. All of these methods still require the user to stand outside in the elements with the attendant exposure to the chemicals being applied. The prior art spreading methods are also very time-consuming, and it is difficult to judge the precise quantities of chemicals being spread over a given area in a given period of time.
Furthermore, hand-held sprayers require pulling a hose around the area to be treated, and also need frequent refilling since only a small amount of chemicals can fit into the hand-held reservoirs. In addition, in some prior art hand-held sprayers, a venturi is located near or in the spray nozzle. This arrangement substantially reduces flow of liquid out of the sprayer, thus slowing the application process.
Large commercial growers may use built-in commercialtype injectors placed on the pressure side of a pump forming part of a liquid distribution system. However, these systems are expensive and tend to reduce the overall flow of liquid through the distribution system.
One solution to these problems is proposed in U.S. Pat. No. 3,669,357 (Overbey) which discloses an injection and distribution unit for a lawn sprinkler system. The unit includes a reservoir, transfer tube and connector which injects liquid fertilizers and pesticides into a lawn sprinkler system. Fluid flowing through the main pipe of the irrigation system creates a suction zone in a transfer tube attached to a chemical reservoir. However, there are no means to control backflow into this reservoir in order to prevent undesirable dilution of the chemical stored in the reservoir, nor is there a means available to control flow out of the reservoir. Once all of the liquid in the reservoir has been exhausted, air will be sucked into the liquid distribution system pump causing liquid flow to slow or stop until the pump is reprimed.
There is thus a need for an agricultural chemical distribution system which can apply the appropriate amount of chemicals over large areas at the appropriate time, while requiring only minimal human contact with the chemicals to be applied, and minimal effort to control the amount and timing of the supply. In addition, there is a need for a chemical distribution system which may be placed in line with a pump for a liquid distribution system that will not affect the performance of the pump by allowing air into the pump or allow backflow from the liquid distribution system. The present invention is directed toward filling these needs.